wall layers wont allow modification

[steve]

I am taking a working wall type and inserting a layer.   I get repeated error message I can find no solution for.   I have been modifying wall types like this for years, can't find a solution.   see jpg

thanks.  

[barthbradley]

You must have another unlocked layer. On the other side? Can't do that.  

Instead of unlocking outer layers on opposite sides of the wall, unlock the core and manipulate its height in relationship to the outer layers.  Get it?  

[ToanDN]

No way you did make a,b, and d Unlocked per your note.  And Wraps has nothing to do with Locking/Unlocking layers.  Which layers you need to unlock now exactly?